A washing machine is a domestic appliance for cleaning clothes, linens, and other laundry. A washing machine may include a tub and a drum positioned in the tub that is sized to receive laundry for cleaning. The washing machine may include an electric motor that causes the drum to rotate relative to the tub during a washing operation. In some washing machines, the electric motor may be connected to the drum via a transmission system including, for example, belts and pulleys. The electric motor may also be connected to the drum via a drive shaft. Washing machines including the latter type of electric motor are often referred to as “direct drive” washing machines.
Electric motors typically include a stator and a rotor configured to rotate relative to the stator. The stator may be fixed to the tub of the washing machine and may include a number of stator coils. The rotor includes one or more magnets that interact with the stator coils. During operation, the stator coils may be sequentially energized with electricity to cause the rotor to rotate. In a direct drive washing machine, the rotor may be torsionally secured to the drive shaft so that drive force may be transferred to the drum via the drive shaft.
Permanent magnet rotors with ferrite magnets have a limited amount of torque that can be delivered per a defined dimension. In order to maximize torque, any several factors may be modified, and one factor that may be modified is the magnetic flux produced by the rotor magnets. One way of improving the magnetic flux is to use an array of Halbach magnets. The physical disposition of different orientation of magnets in a Halbach array may boost the magnetic flux generated, compared with a regular disposition of magnets, by augmenting the magnetic field on one side of the array while reducing or canceling the field on the opposite side of the array.